50 instead of 42 Days for 2nd Jab

My husband went for his first Covid jab on the 31st May at Milpark Hospital in Johannesburg and had a really bad experience there - standing in extremely cold weather for 4 hours in an open parking garage with a roof overhead but very draughty (open on the sides). I said to him, let me book you for your second jab at Discovery 1 Place as I went there and had really good experience. When going online to book the 2nd jab, they require you to enter in the date of your 1st jab (31st May) and they automatically work it out for you. He was booked for the 20th July which worked out to 50 days and not 42 days after the 1st jab - There was no way one could change the date to earlier on their automatic booking. My booking on their website also gave me 50 days. He has now been called back to Milpark (42 days - by the NDHEVDS). My complaint is that I tried to use their Whatsapp and their online app to ask why 50 days and they throw a whole lot of answers at you (by a BOT) that have nothing to do with the question you ask. There is also no way of communicating with a person at Discovery over the weekend - you have to phone in during office hours. So it is now all too little too late for my husband, he now has to go back to Milpark. My question is why 50 days when everywhere it tells you 42 days??